Chapter 1: The Evolution of Microorganisms and Microbiology Vocabulary

Vocabulary flashcards covering key terms, historical figures, and evolutionary concepts from Prescott's Microbiology, 12th Edition, Chapter 1.

Microorganisms

Organisms that are generally smaller than $1\,\text{mm}$ and too small to be clearly seen by the unaided eye, which lack differentiated tissues.

Acellular Biological Entities

Biological entities lacking cellular structure, including viruses (composed of protein and nucleic acid), viroids (composed of RNA), satellites (composed of nucleic acid enclosed in a protein shell), and prions (composed of protein).

Prokaryotic Cells

Cells that feature an open floor plan lacking a membrane-enclosed nucleus.

Eukaryotic Cells

Cells that contain a membrane-enclosed nucleus, and are larger and morphologically more complex than prokaryotic cells.

Domain Bacteria

A domain of usually single-celled organisms that mostly possess cell walls containing peptidoglycan, lack a membrane-bound nucleus, and inhabit diverse environments including the human microbiome.

Domain Archaea

A domain of microbes distinguished from Bacteria by unique rRNA sequences and membrane lipids, many of which live in extreme environments and do not directly cause disease in humans.

Ribozymes

Catalytic RNA molecules that can form peptide bonds and are capable of storing, copying, and expressing genetic information.

RNA World Hypothesis

A proposed precellular evolutionary state in which self-replicating RNA enclosed in lipid vesicles performed both genetic storage and catalytic functions prior to the evolution of DNA and proteins.

Stromatolites

Layered, mineralized structures formed by microbial mats, particularly ancient cyanobacteria.

Last Universal Common Ancestor (LUCA)

The most recent common ancestral organism from which all three domains of cellular life (Bacteria, Archaea, and Eukarya) arose.

Endosymbiotic Theory

The theory stating that eukaryotic organelles such as mitochondria and chloroplasts originated from endosymbiotic bacteria (proteobacteria and cyanobacteria, respectively) living inside early host cells.

Hydrogenosomes

Organelles found in some anaerobic eukaryotes that produce ATP via fermentation and evolved from an anaerobic bacterial endosymbiont.

Small Subunit (SSU) rRNA

Ribosomal RNA sequence used by Carl Woese and other microbiologists to compare evolutionary distance and construct the universal phylogenetic tree of life.

Bootstrapping

A statistical check for accuracy used in character-based approaches when inferring ancestors and constructing phylogenetic trees.

Unrooted Phylogenetic Tree

A phylogenetic tree topology that defines evolutionary relationships between organisms without indicating a common ancestor or age of divergence.

Rooted Phylogenetic Tree

A phylogenetic tree topology containing a node that serves as the common ancestor for all entities in the tree, representing the direction of evolutionary time.

Strain

A population of microbes descending from a single, pure microbial culture that may differ biochemically, morphologically, or pathogenically from other strains of the same species.

Spontaneous Generation

The historical belief that living organisms can develop spontaneously from nonliving or decomposing matter.

Swan-Neck Flask Experiment

Louis Pasteur's famous experiment using curved-neck flasks to demonstrate that nutrient broth remains sterile when exposed to air as long as airborne microbes are trapped in the neck, disproving spontaneous generation.

Koch's Postulates

A set of four criteria established by Robert Koch to prove that a specific microorganism causes a specific disease.

Attenuated Cultures

Pathogenic cultures incubated for extended intervals between transfers, causing them to lose their ability to cause disease while remaining capable of conferring immunity as vaccines.

Sergei Winogradsky

A microbiologist who studied soil microorganisms and discovered key metabolic processes such as nitrogen fixation.

Martinus Beijerinck

A microbiologist who pioneered the use of enrichment cultures and selective media, and proved that a virus causes tobacco mosaic disease.